Reel changer of a web-fed printing press

ABSTRACT

A reel changer of a web-fed printing press includes a load-bearing axle and a carrying arm having at least two carrying-arm segments. A printing-material reel may be mounted or clamped between the carrying-arm segments of the carrying arm. The printing-material reel is displaceable relative to the load-bearing axle using the carrying-arm segments in a production mode. A control system and a safety system which operates independently of the control system both monitor the relative spacing between the carrying-arm segments and blocks the respective carrying-arm segments in the event of an impermissible spacing deviation in the production mode. The safety system includes a separate distance measuring device dedicated to each carrying-arm segment, which distance measuring devices interact with an evaluation device.

BACKGROUND OF THE INVENTION

The present invention relates to a reel changer having a load-bearing axle including at least one carrying arm with two carrying-arm segments, wherein a printing-material reel may be mounted or clamped on the carrying-arm segments of the carrying arm in a loading mode, and the printing-material reel is displaceable relative to the load-bearing axle by the carrying-arm segments in a production mode, and a control system monitoring the relative spacing between the carrying-arm segments of the carrying arm in the production mode and blocking the respective carrying-arm segments in the event of an impermissible spacing deviation.

Reel changers of web-fed printing presses assume primarily three main roles: unwinding a printing-material web from a printing-material reel at a defined web speed; applying a defined web tension to the printing-material web to be unwound; and performing a roll change between a printing-material reel which is running out and a new printing-material reel. Reel changers are also referred to as reel carriers.

To perform a reel change, a new printing-material reel is mounted or clamped on a carrying arm of the reel changer assigned to a load-bearing axle, the clamped printing-material reel subsequently being moved into a working position by pivoting of the load-bearing axle. The position of the load-bearing arm or of the carrying arm, in which a new printing-material reel can be clamped on the carrying arm, is referred to as the loading mode. The working position of the load-bearing axle or of the carrying arm is referred to as the production mode. After a new printing-material reel has been clamped on the carrying arm of the reel changer and has been pivoted into the production mode, the new printing-material reel is accelerated to the circumferential speed of the printing-material reel which is running out and the new printing-material web is adhesively bonded to the printing-material web which is running out. The printing-material web which is running out is then severed with the aid of a dividing knife, and the printing-material reel which is running out is subsequently braked and ejected, whereas the new printing-material reel is active.

A new printing-material reel is clamped on a carrying arm of the reel changer in the loading mode by moving carrying-arm segments of the carrying arm apart and thereby enlarging the relative spacing between them, in order to position a new printing-material reel between the carrying-arm segments. The carrying-arm segments are subsequently moved towards one another by reducing the relative spacing between them to clamp the printing-material reel on what are known as clamping mandrels of the carrying-arm segments of a carrying arm. Accordingly, in the clamped state of a printing-material reel, the carrying-arm segments of the corresponding carrying arm have a defined relative spacing with respect to one another. In the subsequent, further handling of the printing-material reel, this relative spacing is only allowed to change within certain limits, to ensure that a printing-material reel is constantly clamped securely on a carrying arm and accordingly cannot be released from the carrying arm in an unintended manner. An unintended release of a clamped printing-material reel from the carrying arm is a considerable danger for people who are working on the web-fed printing press.

It is already known in practice that a control system of a reel changer, namely what is known as a programmable logic controller (PLC), monitors the relative spacing between the carrying-arm segments of a carrying arm in the production mode with the aid of absolute value encoders and blocks the carrying-arm segments in the event of an impermissible spacing deviation. In order to provide a safety system which operates independently of the control system, it is known in practice, furthermore, to aim light barriers at both sides of a clamped printing-material reel, Using such a safety system it is possible to monitor whether the clamping mandrels move out of the printing-material reel, that is to say whether the spacing changes between the respective side of the printing-material reel and the corresponding carrying-arm segment. However, the use of a safety system of this type which is based on light barriers is disadvantageous for a wide variety of reasons.

For instance, light barriers are very sensitive, have to be cleaned frequently and accordingly require intensive maintenance. Furthermore, intensive and complicated adjustment work is required before commissioning of the light barriers. If a safety system which is based on light barriers is to be suitable for printing-paper reels having different sleeve diameters, a large number of sensors have to be used, as a result of which high costs are incurred.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a reel changer of a web-fed printing press which overcomes the problems of the prior art.

The object is met by a reel changer of a web-fed printing press having a load-bearing axle with at least one carrying arm having two carrying-arm segments, wherein a printing-material reel may be mounted or clamped on the carrying-arm segments of the carrying arm in a loading mode, the printing-material reel being displaceable relative to the load-bearing axle by the carrying-arm segments in a production mode when the printing-material reel is mounted or clamped on the carrying arm. A control system monitors the relative spacing between the carrying-arm segments of the carrying arm in the production mode and blocking the respective carrying-arm segments in the event of an impermissible spacing deviation. The reel changer further comprises a safety system which operates independently of the control system, and also monitors the relative spacing between the carrying-arm segments of the or every carrying arm in the production mode and blocks the respective carrying-arm segments in the event of an impermissible spacing deviation. The safety system operating independently of the control system comprises a distance measuring device for each carrying-arm segment, which distance measuring devices interact with an evaluation device.

In the context of the present invention, a safety system which operates independently of the control system is proposed which monitors the relative spacing between the carrying-arm segments of the respective carrying arm in the production mode on the basis of distance measuring devices and blocks the carrying-arm segments in the event of an impermissible spacing deviation between the said carrying-arm segments. The safety system of the reel changer according to the present invention is substantially less expensive and susceptible to faults than the safety system which is known in practice and is based on light barriers.

There is preferably one encoder per carrying-arm segment, which encoder serves as the position transmitter of the respective carrying-arm segment. The encoders interact with counters, the counters being incremented upwards or downwards as a function of the direction of the displacement of the carrying-arm segments. Encoders and counters form digital distance measuring devices. When the difference between the counters deviates from a setpoint value by a defined amount, an impermissible spacing deviation of the carrying-arm segments can be inferred. In response to the impermissible spacing deviation, the movement of the carrying-arm segments is blocked.

Instead of digital distance measuring devices, analogue distance measuring devices can also be used which use potentiometers as position transmitters of the respective carrying-arm segments, it then being possible to monitor the relative spacing between the carrying-arm segments of the respective carrying arm by comparing the potentiometer values.

According to one embodiment of the present invention, the safety system monitors the relative spacing between the carrying-arm segments of a carrying arm in the loading mode and the production mode, but blocks the carrying-arm segments of the respective carrying arm in the event of an impermissible spacing deviation only in the production mode.

Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, wherein like reference characters denote similar elements throughout the several views:

FIG. 1 is a schematic diagram of a reel changer according to the invention of a web-fed printing press; and

FIG. 2 is a schematic diagram showing a side of a load bearing axle of the reel changer of FIG. 1.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

FIGS. 1 and 2 show details of a reel changer 10 according to the present invention in the region of a load-bearing axle 11 which is rotatable about a longitudinal mid-axis 12 in the direction of the arrow 13 (FIG. 2). A carrying arm 14 assigned to the load-bearing axle 11 is shown in FIG. 1 on which a printing-material reel (not shown) is mounted or clamped. Further carrying arms may be assigned to the load-bearing axle 11 in addition to the carrying arm 14 which is shown in FIG. 1. Two or three carrying arms are usually assigned to the load-bearing axle 11 of a reel changer.

Every carrying arm 14 of the reel changer 10 is formed by preferably two carrying-arm segments 15 and 16. The carrying-arm segments 15 and 16 are mounted on the load-bearing axle 11 such that they are displaceable or moveable parallel to the longitudinal mid-axis 12 of the load-bearing axle 11 in the direction of the arrows 17 and 18. Each of the carrying-arm segments 15 and 16 is driven separately by a motor 31, 32 and a frequency converter (not shown).

The carrying-arm segments 15 and 16 of the carrying arm 14 on the reel changer 10 according to the present invention mount or clamp a printing-material reel for further handling of the printing-material reel during a reel change or when a printing-material web is pulled off from the respective printing-material reel. A printing-material reel is clamped in what is known as a loading mode of the carrying arm 14 or the load-bearing axle 11. The reel change and the pulling off of the printing-material web take place in what is known as a production mode of the carrying arm 14 or the load-bearing axle 11. The loading mode and the production mode are determined according to the rotary position or angular position of the load-bearing axle 11 or of the respective carrying arm 14.

FIGS. 1 and 2 show the carrying arm 14 in what is known as its loading mode, the loading mode being detected by a sensor 19 which is configured as a probe and monitors or senses the angular position of the load-bearing axle 11. The sensor 19 closes a switch 20 in the loading mode, whereas the switch 20 is open in the production mode.

In the loading mode, the two carrying-arm segments 15 and 16 of the carrying arm 14 can be displaced independently of one another in the direction of the arrows 17 and 18, which changes the relative spacing between the said carrying-arm segments 15 and 16. The relative spacing between the carrying-arm segments 15 and 16 can be increased for mounting or clamping a printing-paper reel on the carrying-arm segments 15 and 16 of the carrying arm 14, with the result that a printing-material reel can be positioned between clamping mandrels 21 and 22 of the carrying-arm segments 15 and 16. Subsequently, the carrying-arm segments 15 and 16 are moved towards one another, which reduces the relative spacing between the said carrying-arm segments 15 and 16. This introduces the clamping mandrels 21 and 22 into a sleeve of the printing-material reel, to clamp the printing-material reel between the carrying-arm segments 15 and 16.

A printing-material reel which is clamped on the carrying-arm segments 15 and 16 of the carrying arm 14 in this way can then be transferred by the reel changer by pivoting of the load-bearing axle 11 from the loading mode into the production mode and can be fed to a further handling step. It is important that the spacing between the carrying-arm segments 15 and 16 does not change impermissibly in the production mode, to ensure that a clamped printing-material reel is not detached unintentionally from the carrying arm 14 or the carrying-arm segments 15 and 16.

In the reel changer 10 according to the present invention, the relative position of the carrying-arm segments 15 and 16 can be monitored with the aid of a control system 33 of the reel changer 10.

In the production mode, the control system 33 of the reel changer 10 monitors the relative spacing between the carrying-arm segments 15 and 16 of a carrying arm 14. In the event of an impermissible spacing deviation between the carrying-arm segments 15 and 16, movement of the carrying-arm segments 15, 16 is blocked by blocking either the carrying-arm segments 15, 16 or their motors 31, 32. The control system 33 is configured, in particular, as a PLC control system and monitors the relative spacing between the carrying-arm segments 15 and 16 on the basis of signals which are provided by absolute value encoders 34, 35.

The reel changer 10 further comprises a safety system which operates independently of the control system 33, and likewise monitors the relative spacing between the carrying-arm segments 15 and 16 of a carrying arm 14 in the production mode and blocks the carrying-arm segments 15, 16 or their motors 31, 32 in the event of an impermissible spacing deviation. The safety system which operates independently of the control system comprises a distance measuring device assigned to each carrying-arm segment 15 and 16, which distance measuring devices interact with an evaluation device.

In the preferred exemplary embodiment shown in FIG. 1, the distance measuring devices are configured as digital distance measuring devices and are formed by encoders 23, 24 and counters 25, 26. The safety system which operates independently of the control system thus comprises in each case an encoder 23 and 24 for each carrying-arm segment 15 and 16 of a carrying arm 14. The encoders 23 and 24 form position transmitters of the respective carrying arm segments 15 and 16, respectively. The encoders 23 and 24 interact with in each case one counter 25 and 26, respectively. The counters 25 and 26 are incremented either upwards or downwards via the encoders 23 and 24, respectively, as a function of the displacement of the respective carrying-arm segments 15 and 16 relative to the load-bearing axle 11. For instance, the counters may be incremented upwards in response to a movement to the right and correspondingly incremented downwards in response to a movement to the left.

A difference is formed from the counter readings of the respective counters 25 and 26 in a block or evaluation device 27, the difference between the counters 25 and 26 determining the relative spacing between the carrying-arm segments 15 and 16 of a carrying arm 14. An impermissible spacing deviation of the carrying-arm segments 15 and 16 is inferred if the difference between the counter readings of the counters 25 and 26 deviates from a setpoint value by a defined amount in the production mode. In this case, the evaluation device 27 or the safety system which operates independently of the control system then blocks the carrying-arm segments 15 and 16 or the motors 31, 32. Otherwise, the carrying-arm segments 15 and 16 can displace or move a clamped printing-material reel relative to the load-bearing axis 11 while retaining their relative spacing with respect to one another.

The abovementioned setpoint value for the difference between the counters 25 and 26 and thus the setpoint distance between the carrying-arm segments 15 and 16 are determined from the spacing of the carrying-arm segments 15 and 16 after the clamping of a printing-material reel on the carrying arm 14 in the loading mode. In order to determine this setpoint value, the safety system also monitors the relative spacing between the carrying-arm segments 15 and 16 in the loading mode by incrementation of the respective counters 25 and 26. The evaluation device 27 causes the carrying-arm segments 15 and 16 to be blocked only in the production mode, i.e., when switch 20 is opened and when an impermissible spacing deviation is inferred. In the loading mode, i.e., when switch 20 is closed, the carrying-arm segments 15 and 16 are allowed to be displaced even if the counter readings 25 and 26 indicate that the spacing between the carrying-arm segments 15 and 16 is increased by an amount which is impermissible in the production mode.

Finally, it should be pointed out that the carrying-arm segments 15 and 16 of the carrying arm 14 are blocked when either the control system 33 or the safety system which operates independently of the control system 33 detects an impermissible spacing deviation between the carrying-arm segments in the production mode.

Thus, while there have shown and described and pointed out fundamental novel features of the invention as applied to a preferred embodiment thereof, it will be understood that various omissions and substitutions and changes in the form and details of the devices illustrated, and in their operation, may be made by those skilled in the art without departing from the spirit of the invention. For example, it is expressly intended that all combinations of those elements which perform substantially the same function in substantially the same way to achieve the same results are within the scope of the invention. Moreover, it should be recognized that structures and/or elements shown and/or described in connection with any disclosed form or embodiment of the invention may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto. 

1. A reel changer of a web-fed printing press, comprising: a load-bearing axle including a carrying arm having at least two carrying-arm segments, said load bearing axle being movable for moving said carrying arm between a loading mode and a production mode, said carrying arm being arranged and dimensioned for receiving a printing-material reel in said loading mode, whereby the printing material reel is mountable or clampable between said carrying-arm segments in the loading mode, and said carrying arm being further arranged and dimensioned such that said carrying-arm segments are displaceable relative to said load-bearing axle in said production mode, whereby the printing-material reel is displaceable relative to said load-bearing axle by said carrying-arm segments; a control system monitoring a relative spacing between said carrying-arm segments in said production mode and blocking movement of said carrying-arm segments in the event of an impermissible spacing deviation; and a safety system operating independently of said control system, said safety system comprising distance measuring devices connected to an evaluation device for monitoring the relative spacing between said carrying-arm segments in the production mode and blocking movement of said carrying-arm segments in the event of an impermissible spacing deviation, each of said distance measuring devices corresponding to a respective one of said carrying-arm segments.
 2. The reel changer of claim 1, wherein each of said distance measuring devices of said safety system comprises one encoder and one counter, said encoders comprising position transmitters of said respective carrying-arm segments and incrementing said counters upwards or downwards in response to a direction of displacement of said carrying-arm segments, wherein said evaluation device infers an impermissible spacing deviation of said carrying-arm segments and blocking movement of said carrying-arm segments if the difference between the counters deviates from a setpoint value by a defined amount.
 3. The reel changer of claim 2, wherein said evaluation device includes a subtractor which subtracts the counter readings of said counters and monitors whether the difference between said counters deviates from the setpoint value by the defined amount.
 4. The reel changer of claim 2, wherein the setpoint value is determined from a spacing between said carrying-arm segments after a printing-material reel is mounted or clamped on said carrying arm in said loading mode.
 5. The reel changer of claim 1, wherein said control system comprises absolute value encoders as position transmitters of said carrying-arm segments.
 6. The reel changer of claim 1, wherein said safety system monitors the relative spacing between said carrying-arm segments of said carrying arm in said loading mode and said production mode, and blocks movement of said carrying-arm segments of said carrying arm in the event of an impermissible spacing deviation only in said production mode.
 7. The reel changer of claim 1, wherein said loading mode and said production mode are determined as a function of an angular position of the load-bearing axle.
 8. The reel changer of claim 1, further comprising a separate motor for driving each of said carrying-arm segments, wherein at least one of said control system and said safety system block said motors in the production mode in the event of an impermissible spacing deviation to block movement of said carrying-arm segments. 